cmd/dist: support spaces and quotes in CC
As of CL 334732 `go build` can accept `$CC` with spaces and quotes,
which lets us easily use `zig cc` as the C compiler, or easily pass
extra compiler parameters:
```
CC="zig cc" go build <...>
CC="clang-13 -v" go build <...>
CC="zig cc -Wl,--print-gc-sections" go build <...>
```
However, the same does not apply for building go itself:
```
$ CC="zig cc" ./make.bash
Building Go cmd/dist using /usr/local/go. (go1.18.2 linux/amd64)
go tool dist: cannot invoke C compiler "zig cc": exec: "zig cc": executable file not found in $PATH
Go needs a system C compiler for use with cgo.
To set a C compiler, set CC=the-compiler.
To disable cgo, set CGO_ENABLED=0.
```
With this change Go can be built directly with `zig cc` (the linker arg
will disappear with CL 405414):
```
$ CC="zig cc -Wl,--no-gc-sections" ./make.bash
Building Go cmd/dist using /usr/local/go. (go1.18.2 linux/amd64)
Building Go toolchain1 using /usr/local/go.
Building Go bootstrap cmd/go (go_bootstrap) using Go toolchain1.
Building Go toolchain2 using go_bootstrap and Go toolchain1.
Building Go toolchain3 using go_bootstrap and Go toolchain2.
Building packages and commands for linux/amd64.
---
Installed Go for linux/amd64 in /home/motiejus/code/go
Installed commands in /home/motiejus/code/go/bin
$ ../bin/go version
go version devel go1.19-
811f1913a8 Thu May 19 09:44:49 2022 +0300 linux/amd64
```
Fixes #52990
Change-Id: I66b3525d47db488d3c583c1aee3af78060fd5a38
GitHub-Last-Rev:
ecc70d722406f0c7d0c1930c872db392e80e7cf5
GitHub-Pull-Request: golang/go#52991
Reviewed-on: https://go-review.googlesource.com/c/go/+/407216
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Alex Rakoczy <alex@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>